Navigated surgical system with eye to xr headset display calibration

ABSTRACT

A camera tracking system for computer assisted navigation during surgery operatively determines a first pose of a second extended-reality (XR) headset relative to stereo tracking cameras located on a first XR headset based on first tracking information from the stereo tracking cameras. The camera tracking system determines a second pose of eyes of a user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset based on second tracking information from the stereo tracking cameras. The camera tracking system also calibrates an eye-to-display relationship defining pose of the eyes of the user wearing the second XR headset to a display device of the second XR headset based on the determined first and second poses. The camera tracking system also controls where symbols are displayed on the display device of the second XR headset based on the eye-to-display relationship.

FIELD

The present disclosure relates to medical devices and systems, and more particularly, camera tracking systems used for computer assisted navigation during surgery.

BACKGROUND

Computer assisted navigation in surgery provides surgeons with enhanced visualization of surgical instruments with respect to radiographic images of the patient's anatomy. Navigated surgeries typically include components for tracking the position and orientation of surgical instruments via arrays of disks or spheres using a single stereo camera system.

Eye tracking can have major advantages in wearable extended reality display systems. Eye tracking allows for more accurate overlays of virtual content displayed on the physical world, and proper warping of the frames being sent to the displays for more realistic content.

Eye tracking, unfortunately, can be expensive, bulky, and difficult to integrate. It normally requires 2-4 cameras as well as infrared strobes which need to see/shine on the pupils to be mounted inside of a headset. This set up requires specific positioning of the eye tracker which may not be possible in certain headset/optic designs. One additional downfall to adding the necessary equipment is that the additions also increase the weight and size of an augmented reality headset.

SUMMARY

Various embodiments disclosed herein are directed to improvements in eye tracking for calibrating pose of a user's eyes to a display device of an extended reality (XR) headset during computer assisted navigation during surgery.

In one embodiment, a camera tracking system for computer assisted navigation during surgery operatively determines a first pose of a second XR headset relative to stereo tracking cameras located on a first XR headset based on first tracking information from the stereo tracking cameras. The camera tracking system determines a second pose of eyes of a user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset based on second tracking information from the stereo tracking cameras. The camera tracking system also calibrates an eye-to-display relationship defining pose of the eyes of the user wearing the second XR headset to a display device of the second XR headset based on the determined first and second poses. The camera tracking system also controls where symbols are displayed on the display device of the second XR headset based on the eye-to-display relationship.

Related methods by a camera tracking system and related computer program products are disclosed.

Other camera tracking systems, methods, and computer program products according to embodiments will be or become apparent to one with skill in the art upon review of the following drawings and detailed description. It is intended that all such camera tracking systems, methods, and computer program products be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. Moreover, it is intended that all embodiments disclosed herein can be implemented separately or combined in any way and/or combination.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in a constitute a part of this application, illustrate certain non-limiting embodiments of inventive concepts. In the drawings:

FIG. 1 illustrates an embodiment of a surgical system according to some embodiments of the present disclosure;

FIG. 2 illustrates a surgical robot component of the surgical system of FIG. 1 according to some embodiments of the present disclosure;

FIG. 3A illustrates a camera tracking system component of the surgical system of FIG. 1 according to some embodiments of the present disclosure;

FIGS. 3B and 3C illustrate a front view and isometric view of another camera tracking system component which may be used with the surgical system of FIG. 1 according to some embodiments of the present disclosure;

FIG. 4 illustrates an embodiment of an end effector that is connectable to a robot arm and configured according to some embodiments of the present disclosure;

FIG. 5 illustrates a medical operation in which a surgical robot and a camera system are disposed around a patient;

FIG. 6 illustrates a block diagram view of the components of the surgical system of FIG. 5 being used for a medical operation;

FIG. 7 illustrates various display screens that may be displayed on the display of FIGS. 5 and 6 when using a navigation function of the surgical system;

FIG. 8 illustrates a block diagram of some electrical components of a surgical robot according to some embodiments of the present disclosure;

FIG. 9 illustrates a block diagram of components of a surgical system that includes imaging devices connected to a computer platform which can be operationally connected to a camera tracking system and/or surgical robot according to some embodiments of the present disclosure;

FIG. 10 illustrates an embodiment of a C-Arm imaging device that can be used in combination with the surgical robot in accordance with some embodiments of the present disclosure;

FIG. 11 illustrates an embodiment of an O-Arm imaging device that can be used in combination with the surgical robot in accordance with some embodiments of the present disclosure;

FIG. 12 illustrates a block diagram view of the components of a surgical system that includes a pair of XR headsets and an auxiliary tracking bar which operate in accordance with some embodiments of the present disclosure;

FIG. 13 illustrates an XR headset which is configured in accordance with some embodiments of the present disclosure;

FIG. 14 illustrates electrical components of the XR headset that can be operatively connected to a computer platform, imaging device(s), and/or a surgical robot in accordance with some embodiments of the present disclosure;

FIG. 15 illustrates a block diagram showing arrangement of optical components of the XR headset in accordance with some embodiments of the present disclosure;

FIG. 16 illustrates an example view through the display screen of an XR headset for providing navigation assistance to manipulate a surgical tool during a medical procedure in accordance with some embodiments of the present disclosure;

FIG. 17 illustrates an example configuration of an auxiliary tracking bar having two pairs of stereo cameras configured in accordance with some embodiments of the present disclosure;

FIG. 18 illustrates a block diagram view of the components of a surgical system that includes tracking cameras in a pair of XR headsets and in an auxiliary tracking bar which collectively operate in accordance with some embodiments of the present disclosure;

FIG. 19 illustrates an embodiment of two users wearing XR headsets operative to track each other's eyes in accordance with some embodiments of the present disclosure;

FIG. 20 illustrates an embodiment of one user wearing an XR headset operative to tracking the user's eyes using a reflective surface accordance with some embodiments of the present disclosure;

FIG. 21 illustrates an embodiment of tracking coordinate systems for two XR headsets in accordance with some embodiments of the present disclosure; and

FIGS. 22, 23, and 24 illustrate flow charts of operations performed by a camera tracking system for calibrating eye-to-XR headset displays and responsively controlling where symbols are displayed on XR headsets in accordance with some embodiments.

DETAILED DESCRIPTION

Inventive concepts will now be described more fully hereinafter with reference to the accompanying drawings, in which examples of embodiments of inventive concepts are shown. Inventive concepts may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of various present inventive concepts to those skilled in the art. It should also be noted that these embodiments are not mutually exclusive. Components from one embodiment may be tacitly assumed to be present or used in another embodiment.

Various embodiments disclosed herein are directed to improvements in computer assisted navigation during surgery. An extended reality (XR) headset is operatively connected to the surgical system and configured to provide an interactive environment through which a surgeon, assistant, and/or other personnel can view and select among patient images, view and select among computer generated surgery navigation information, and/or control surgical equipment in the operating room. As will be explained below, the XR headset may be configured to augment a real-world scene with computer generated XR images. The XR headset may be configured to provide an augmented reality (AR) viewing environment by displaying the computer generated XR images on a see-through display screen that allows light from the real-world scene to pass therethrough for combined viewing by the user. Alternatively, the XR headset may be configured to provide a virtual reality (VR) viewing environment by preventing or substantially preventing light from the real-world scene from being directly viewed by the user while the user is viewing the computer generated AR images on a display screen. An XR headset can be configured to provide both AR and VR viewing environments. In one embodiment, both AR and VR viewing environments are provided by lateral bands of substantially differing opacity arranged between the see-through display screen and the real-world scene, so that a VR viewing environment is provided for XR images aligned with a high opacity band and an AR viewing environment is provided for XR images aligned with the low opacity band. In another embodiment, both AR and VR viewing environments are provided by computer adjustable control of an opacity filter that variably constrains how much light from the real-world scene passes through a see-through display screen for combining with the XR images viewed by the user. Thus, the XR headset can also be referred to as an AR headset or a VR headset.

FIG. 1 illustrates an embodiment of a surgical system 2 according to some embodiments of the present disclosure. Prior to performance of an orthopedic or other surgical procedure, a three-dimensional (“3D”) image scan may be taken of a planned surgical area of a patient using, e.g., the C-Arm imaging device 104 of FIG. 10 or O-Arm imaging device 106 of FIG. 11, or from another medical imaging device such as a computed tomography (CT) image or MRI. This scan can be taken pre-operatively (e.g. few weeks before procedure, most common) or intra-operatively. However, any known 3D or 2D image scan may be used in accordance with various embodiments of the surgical system 2. The image scan is sent to a computer platform in communication with the surgical system 2, such as the computer platform 910 of the surgical system 900 (FIG. 9) which may include the camera tracking system component 6, the surgical robot 4 (e.g., robot 2 in FIG. 1), imaging devices (e.g., C-Arm 104, O-Arm 106, etc.), and an image database 950 for storing image scans of patients. A surgeon reviewing the image scan(s) on a display device of the computer platform 910 (FIG. 9) generates a surgical plan defining a target pose for a surgical tool to be used during a surgical procedure on an anatomical structure of the patient. Example surgical tools, also referred to as tools, can include, without limitation, drills, screw drivers, retractors, and implants such as a screws, spacers, interbody fusion devices, plates, rods, etc. In some embodiments, the surgical plan defining the target plane is planned on the 3D image scan displayed on a display device.

As used herein, the term “pose” refers to the position and/or the rotational angle of one object (e.g., dynamic reference array, end effector, surgical tool, anatomical structure, etc.) relative to another object and/or to a defined coordinate system. A pose may therefore be defined based on only the multidimensional position of one object relative to another object and/or to a defined coordinate system, only on the multidimensional rotational angles of the object relative to another object and/or to a defined coordinate system, or on a combination of the multidimensional position and the multidimensional rotational angles. The term “pose” therefore is used to refer to position, rotational angle, or combination thereof.

The surgical system 2 of FIG. 1 can assist surgeons during medical procedures by, for example, holding tools, aligning tools, using tools, guiding tools, and/or positioning tools for use. In some embodiments, surgical system 2 includes a surgical robot 4 and a camera tracking system component 6. The ability to mechanically couple surgical robot 4 and camera tracking system component 6 can allow for surgical system 2 to maneuver and move as a single unit, and allow surgical system 2 to have a small footprint in an area, allow easier movement through narrow passages and around turns, and allow storage within a smaller area.

A surgical procedure may begin with the surgical system 2 moving from medical storage to a medical procedure room. The surgical system 2 may be maneuvered through doorways, halls, and elevators to reach a medical procedure room. Within the room, the surgical system 2 may be physically separated into two separate and distinct systems, the surgical robot 4 and the camera tracking system component 6. Surgical robot 4 may be positioned adjacent the patient at any suitable location to properly assist medical personnel. Camera tracking system component 6 may be positioned at the base of the patient, at the patient shoulders, or any other location suitable to track the present pose and movement of the pose of tracks portions of the surgical robot 4 and the patient. Surgical robot 4 and camera tracking system component 6 may be powered by an onboard power source and/or plugged into an external wall outlet.

Surgical robot 4 may be used to assist a surgeon by holding and/or using tools during a medical procedure. To properly utilize and hold tools, surgical robot 4 may rely on a plurality of motors, computers, and/or actuators to function properly. Illustrated in FIG. 1, robot body 8 may act as the structure in which the plurality of motors, computers, and/or actuators may be secured within surgical robot 4. Robot body 8 may also provide support for robot telescoping support arm 16. The size of robot body 8 may provide a solid platform supporting attached components, and may house, conceal, and protect the plurality of motors, computers, and/or actuators that may operate attached components.

Robot base 10 may act as a lower support for surgical robot 4. In some embodiments, robot base 10 may support robot body 8 and may attach robot body 8 to a plurality of powered wheels 12. This attachment to wheels may allow robot body 8 to move in space efficiently. Robot base 10 may run the length and width of robot body 8. Robot base 10 may be about two inches to about 10 inches tall. Robot base 10 may cover, protect, and support powered wheels 12.

In some embodiments, as illustrated in FIG. 1, at least one powered wheel 12 may be attached to robot base 10. Powered wheels 12 may attach to robot base 10 at any location. Each individual powered wheel 12 may rotate about a vertical axis in any direction. A motor may be disposed above, within, or adjacent to powered wheel 12. This motor may allow for surgical system 2 to maneuver into any location and stabilize and/or level surgical system 2. A rod, located within or adjacent to powered wheel 12, may be pressed into a surface by the motor. The rod, not pictured, may be made of any suitable metal to lift surgical system 2. The rod may lift powered wheel 10, which may lift surgical system 2, to any height required to level or otherwise fix the orientation of the surgical system 2 in relation to a patient. The weight of surgical system 2, supported through small contact areas by the rod on each wheel, prevents surgical system 2 from moving during a medical procedure. This rigid positioning may prevent objects and/or people from moving surgical system 2 by accident.

Moving surgical system 2 may be facilitated using robot railing 14. Robot railing 14 provides a person with the ability to move surgical system 2 without grasping robot body 8. As illustrated in FIG. 1, robot railing 14 may run the length of robot body 8, shorter than robot body 8, and/or may run longer the length of robot body 8. Robot railing 14 may further provide protection to robot body 8, preventing objects and or personnel from touching, hitting, or bumping into robot body 8.

Robot body 8 may provide support for a Selective Compliance Articulated Robot Arm, hereafter referred to as a “SCARA.” A SCARA 24 may be beneficial to use within the surgical system 2 due to the repeatability and compactness of the robotic arm. The compactness of a SCARA may provide additional space within a medical procedure, which may allow medical professionals to perform medical procedures free of excess clutter and confining areas. SCARA 24 may comprise robot telescoping support 16, robot support arm 18, and/or robot arm 20. Robot telescoping support 16 may be disposed along robot body 8. As illustrated in FIG. 1, robot telescoping support 16 may provide support for the SCARA 24 and display 34. In some embodiments, robot telescoping support 16 may extend and contract in a vertical direction. The body of robot telescoping support 16 may be any width and/or height configured to support the stress and weight placed upon it.

In some embodiments, medical personnel may move SCARA 24 through a command submitted by the medical personnel. The command may originate from input received on display 34, a tablet, and/or an XR headset (e.g., headset 920 in FIG. 9) as will be explained in further detail below. The XR headset may eliminate the need for medical personnel to refer to any other display such as the display 34 or a tablet, which enables the SCARA 24 to be configured without the display 34 and/or the tablet. The command may be generated by the depression of a switch and/or the depression of a plurality of switches, and/or may be generated based on a hand gesture command and/or voice command that is sensed by the XR headset as will be explained in further detail below.

As shown in FIG. 5, an activation assembly 60 may include a switch and/or a plurality of switches. The activation assembly 60 may be operable to transmit a move command to the SCARA 24 allowing an operator to manually manipulate the SCARA 24. When the switch, or plurality of switches, is depressed the medical personnel may have the ability to move SCARA 24 through applied hand movements. Alternatively or additionally, an operator may control movement of the SCARA 24 through hand gesture commands and/or voice commands that are sensed by the XR headset as will be explained in further detail below. Additionally, when the SCARA 24 is not receiving a command to move, the SCARA 24 may lock in place to prevent accidental movement by personnel and/or other objects. By locking in place, the SCARA 24 provides a solid platform through which the end effector 26 can guide a surgical tool during a medical procedure.

Robot support arm 18 can be connected to robot telescoping support 16 by various mechanisms. In some embodiments, best seen in FIGS. 1 and 2, robot support arm 18 rotates in any direction in regard to robot telescoping support 16. Robot support arm 18 may rotate three hundred and sixty degrees around robot telescoping support 16. Robot arm 20 may connect to robot support arm 18 at any suitable location and by various mechanisms that enable rotation in any direction relative to robot support arm 18. In one embodiment, the robot arm 20 can rotate three hundred and sixty degrees relative to the robot support arm 18. This free rotation allows an operator to position robot arm 20 according to a surgical plan.

The end effector 26 shown in FIGS. 4 and 5 may attach to robot arm 20 in any suitable location. The end effector 26 can be configured to attach to an end effector coupler 22 of the robot arm 20 positioned by the surgical robot 4. The example end effector 26 includes a tubular guide that guides movement of an inserted surgical tool relative to an anatomical structure on which a surgical procedure is to be performed.

In some embodiments, a dynamic reference array 52 is attached to the end effector 26. Dynamic reference arrays, also referred to as “DRAB” herein, are rigid bodies which may be disposed on an anatomical structure (e.g., bone) of a patient, one or more XR headsets being worn by personnel in the operating room, the end effector, the surgical robot, a surgical tool in a navigated surgical procedure. The computer platform 910 in combination with the camera tracking system component 6 or other 3D localization system are configured to track in real-time the pose (e.g., positions and rotational orientations) of the DRA. The DRA can include fiducials, such as the illustrated arrangement of balls. This tracking of 3D coordinates of the DRA can allow the surgical system 2 to determine the pose of the DRA in any multidimensional space in relation to the target anatomical structure of the patient 50 in FIG. 5.

As illustrated in FIG. 1, a light indicator 28 may be positioned on top of the SCARA 24. Light indicator 28 may illuminate as any type of light to indicate “conditions” in which surgical system 2 is currently operating. In some embodiments, the light may be produced by LED bulbs, which may form a ring around light indicator 28. Light indicator 28 may comprise a fully permeable material that can let light shine through the entirety of light indicator 28. Light indicator 28 may be attached to lower display support 30. Lower display support 30, as illustrated in FIG. 2 may allow an operator to maneuver display 34 to any suitable location. Lower display support 30 may attach to light indicator 28 by any suitable mechanism. In some embodiments, lower display support 30 may rotate about light indicator 28 or be rigidly attached thereto. Upper display support 32 may attach to lower display support 30 by any suitable mechanism.

In some embodiments, a tablet may be used in conjunction with display 34 and/or without display 34. The tablet may be disposed on upper display support 32, in place of display 34, and may be removable from upper display support 32 during a medical operation. In addition the tablet may communicate with display 34. The tablet may be able to connect to surgical robot 4 by any suitable wireless and/or wired connection. In some embodiments, the tablet may be able to program and/or control surgical system 2 during a medical operation. When controlling surgical system 2 with the tablet, all input and output commands may be duplicated on display 34. The use of a tablet may allow an operator to manipulate surgical robot 4 without having to move around patient 50 and/or to surgical robot 4.

As will be explained below, in some embodiments a surgeon and/or other personnel can wear XR headsets that may be used in conjunction with display 34 and/or a tablet or the XR head(s) may eliminate the need for use of the display 34 and/or tablet.

As illustrated in FIGS. 3A and 5, camera tracking system component 6 works in conjunction with surgical robot 4 through wired or wireless communication networks. Referring to FIGS. 1, 3 and 5, camera tracking system component 6 can include some similar components to the surgical robot 4. For example, camera body 36 may provide the functionality found in robot body 8. Robot body 8 may provide an auxiliary tracking bar upon which cameras 46 are mounted. The structure within robot body 8 may also provide support for the electronics, communication devices, and power supplies used to operate camera tracking system component 6. Camera body 36 may be made of the same material as robot body 8. Camera tracking system component 6 may communicate directly to an XR headset, tablet and/or display 34 by a wireless and/or wired network to enable the XR headset, tablet and/or display 34 to control the functions of camera tracking system component 6.

Camera body 36 is supported by camera base 38. Camera base 38 may function as robot base 10. In the embodiment of FIG. 1, camera base 38 may be wider than robot base 10. The width of camera base 38 may allow for camera tracking system component 6 to connect with surgical robot 4. As illustrated in FIG. 1, the width of camera base 38 may be large enough to fit outside robot base 10. When camera tracking system component 6 and surgical robot 4 are connected, the additional width of camera base 38 may allow surgical system 2 additional maneuverability and support for surgical system 2.

As with robot base 10, a plurality of powered wheels 12 may attach to camera base 38. Powered wheel 12 may allow camera tracking system component 6 to stabilize and level or set fixed orientation in regards to patient 50, similar to the operation of robot base 10 and powered wheels 12. This stabilization may prevent camera tracking system component 6 from moving during a medical procedure and may keep cameras 46 on the auxiliary tracking bar from losing track of a DRA connected to an XR headset and/or the surgical robot 4, and/or losing track of one or more DRAs 52 connected to an anatomical structure 54 and/or tool 58 within a designated area 56 as shown in FIGS. 3A and 5. This stability and maintenance of tracking enhances the ability of surgical robot 4 to operate effectively with camera tracking system component 6. Additionally, the wide camera base 38 may provide additional support to camera tracking system component 6. Specifically, a wide camera base 38 may prevent camera tracking system component 6 from tipping over when cameras 46 is disposed over a patient, as illustrated in FIGS. 3A and 5.

Camera telescoping support 40 may support cameras 46 on the auxiliary tracking bar. In some embodiments, telescoping support 40 moves cameras 46 higher or lower in the vertical direction. Camera handle 48 may be attached to camera telescoping support 40 at any suitable location and configured to allow an operator to move camera tracking system component 6 into a planned position before a medical operation. In some embodiments, camera handle 48 is used to lower and raise camera telescoping support 40. Camera handle 48 may perform the raising and lowering of camera telescoping support 40 through the depression of a button, switch, lever, and/or any combination thereof.

Lower camera support arm 42 may attach to camera telescoping support 40 at any suitable location, in embodiments, as illustrated in FIG. 1, lower camera support arm 42 may rotate three hundred and sixty degrees around telescoping support 40. This free rotation may allow an operator to position cameras 46 in any suitable location. Lower camera support arm 42 may connect to telescoping support 40 by any suitable mechanism. Lower camera support arm 42 may be used to provide support for cameras 46. Cameras 46 may be attached to lower camera support arm 42 by any suitable mechanism. Cameras 46 may pivot in any direction at the attachment area between cameras 46 and lower camera support arm 42. In embodiments a curved rail 44 may be disposed on lower camera support arm 42.

Curved rail 44 may be disposed at any suitable location on lower camera support arm 42. As illustrated in FIG. 3A, curved rail 44 may attach to lower camera support arm 42 by any suitable mechanism. Curved rail 44 may be of any suitable shape, a suitable shape may be a crescent, circular, oval, elliptical, and/or any combination thereof. Cameras 46 may be moveably disposed along curved rail 44. Cameras 46 may attach to curved rail 44 by, for example, rollers, brackets, braces, motors, and/or any combination thereof. Motors and rollers, not illustrated, may be used to move cameras 46 along curved rail 44. As illustrated in FIG. 3A, during a medical procedure, if an object prevents cameras 46 from viewing one or more DRAs being tracked, the motors may responsively move cameras 46 along curved rail 44. This motorized movement may allow cameras 46 to move to a new position that is no longer obstructed by the object without moving camera tracking system component 6. While cameras 46 is obstructed from viewing one or more tracked DRAs, camera tracking system component 6 may send a stop signal to a surgical robot 4, XR headset, display 34, and/or a tablet. The stop signal may prevent SCARA 24 from moving until cameras 46 has reacquired tracked DRAs 52 and/or can warn an operator wearing the XR headset and/or viewing the display 34 and/or the tablet. This SCARA 24 can be configured to respond to receipt of a stop signal by stopping further movement of the base and/or end effector coupler 22 until the camera tracking system can resume tracking of DRAs.

FIGS. 3B and 3C illustrate a front view and isometric view of another camera tracking system component 6′ which may be used with the surgical system of FIG. 1 or may be used independent of a surgical robot. For example, the camera tracking system component 6′ may be used for providing navigated surgery without use of robotic guidance. One of the differences between the camera tracking system component 6′ of FIGS. 3B and 3C and the camera tracking system component 6 of FIG. 3A, is that the camera tracking system component 6′ of FIGS. 3B and 3C includes a housing that transports the computer platform 910. The computer platform 910 can be configured to perform camera tracking operations to track DRAs, perform navigated surgery operations that provide surgical navigation information to a display device, e.g., XR headset and/or other display device, and perform other computational operations disclosed herein. The computer platform 910 can therefore include a navigation computer, such as one or more of the navigation computers of FIG. 14.

FIG. 6 illustrates a block diagram view of the components of the surgical system of FIG. 5 used for the medical operation. Referring to FIG. 6, the tracking cameras 46 on the auxiliary tracking bar has a navigation field-of-view 600 in which the pose (e.g., position and orientation) of the reference array 602 attached to the patient, the reference array 604 attached to the surgical instrument, and the robot arm 20 are tracked. The tracking cameras 46 may be part of the camera tracking system component 6′ of FIGS. 3B and 3C, which includes the computer platform 910 configured to perform the operations described below. The reference arrays enable tracking by reflecting light in known patterns, which are decoded to determine their respective poses by the tracking subsystem of the surgical robot 4. If the line-of-sight between the patient reference array 602 and the tracking cameras 46 in the auxiliary tracking bar is blocked (for example, by a medical personnel, instrument, etc.), further navigation of the surgical instrument may not be able to be performed and a responsive notification may temporarily halt further movement of the robot arm 20 and surgical robot 4, display a warning on the display 34, and/or provide an audible warning to medical personnel. The display 34 is accessible to the surgeon 610 and assistant 612 but viewing requires a head to be turned away from the patient and for eye focus to be changed to a different distance and location. The navigation software may be controlled by a tech personnel 614 based on vocal instructions from the surgeon.

FIG. 7 illustrates various display screens that may be displayed on the display 34 of FIGS. 5 and 6 by the surgical robot 4 when using a navigation function of the surgical system 2. The display screens can include, without limitation, patient radiographs with overlaid graphical representations of models of instruments that are positioned in the display screens relative to the anatomical structure based on a developed surgical plan and/or based on poses of tracked reference arrays, various user selectable menus for controlling different stages of the surgical procedure and dimension parameters of a virtually projected implant (e.g. length, width, and/or diameter).

For navigated surgery, various processing components (e.g., computer platform 910) and associated software described below are provided that enable pre-operatively planning of a surgical procedure, e.g., implant placement, and electronic transfer of the plan to computer platform 910 to provide navigation information to one or more users during the planned surgical procedure.

For robotic navigation, various processing components (e.g., computer platform 910) and associated software described below are provided that enable pre-operatively planning of a surgical procedure, e.g., implant placement, and electronic transfer of the plan to the surgical robot 4. The surgical robot 4 uses the plan to guide the robot arm 20 and connected end effector 26 to provide a target pose for a surgical tool relative to a patient anatomical structure for a step of the planned surgical procedure.

Various embodiments below are directed to using one or more XR headsets that can be worn by the surgeon 610, the assistant 612, and/or other medical personnel to provide an improved user interface for receiving information from and/or providing control commands to the surgical robot, the camera tracking system component 6/6′, and/or other medical equipment in the operating room.

FIG. 8 illustrates a block diagram of some electrical components of the surgical robot 4 according to some embodiments of the present disclosure. Referring to FIG. 8, a load cell (not shown) may be configured to track force applied to end effector coupler 22. In some embodiments the load cell may communicate with a plurality of motors 850, 851, 852, 853, and/or 854. As load cell senses force, information as to the amount of force applied may be distributed from a switch array and/or a plurality of switch arrays to a controller 846. Controller 846 may take the force information from load cell and process it with a switch algorithm. The switch algorithm is used by the controller 846 to control a motor driver 842. The motor driver 842 controls operation of one or more of the motors 850, 851, 852, 853, and 854. Motor driver 842 may direct a specific motor to produce, for example, an equal amount of force measured by load cell through the motor. In some embodiments, the force produced may come from a plurality of motors, e.g., 850-854, as directed by controller 846. Additionally, motor driver 842 may receive input from controller 846. Controller 846 may receive information from load cell as to the direction of force sensed by load cell. Controller 846 may process this information using a motion controller algorithm. The algorithm may be used to provide information to specific motor drivers 842. To replicate the direction of force, controller 846 may activate and/or deactivate certain motor drivers 842. Controller 846 may control one or more motors, e.g. one or more of 850-854, to induce motion of end effector 26 in the direction of force sensed by load cell. This force-controlled motion may allow an operator to move SCARA 24 and end effector 26 effortlessly and/or with very little resistance. Movement of end effector 26 can be performed to position end effector 26 in any suitable pose (i.e., location and angular orientation relative to defined three-dimensional (3D) orthogonal reference axes) for use by medical personnel.

Activation assembly 60, best illustrated in FIG. 5, may form of a bracelet that wraps around end effector coupler 22. The activation assembly 60 may be located on any part of SCARA 24, any part of end effector coupler 22, may be worn by medical personnel (and communicate wirelessly), and/or any combination thereof. Activation assembly 60 may comprise of a primary button and a secondary button.

Depressing primary button may allow an operator to move SCARA 24 and end effector coupler 22. According to one embodiment, once set in place, SCARA 24 and end effector coupler 22 may not move until an operator programs surgical robot 4 to move SCARA 24 and end effector coupler 22, or is moved using primary button. In some examples, it may require the depression of at least two non-adjacent primary activation switches before SCARA 24 and end effector coupler 22 will respond to operator commands. Depression of at least two primary activation switches may prevent the accidental movement of SCARA 24 and end effector coupler 22 during a medical procedure.

Activated by primary button, load cell may measure the force magnitude and/or direction exerted upon end effector coupler 22 by an operator, i.e. medical personnel. This information may be transferred to one or more motors, e.g. one or more of 850-854, within SCARA 24 that may be used to move SCARA 24 and end effector coupler 22. Information as to the magnitude and direction of force measured by load cell may cause the one or more motors, e.g. one or more of 850-854, to move SCARA 24 and end effector coupler 22 in the same direction as sensed by the load cell. This force-controlled movement may allow the operator to move SCARA 24 and end effector coupler 22 easily and without large amounts of exertion due to the motors moving SCARA 24 and end effector coupler 22 at the same time the operator is moving SCARA 24 and end effector coupler 22.

In some examples, a secondary button may be used by an operator as a “selection” device. During a medical operation, surgical robot 4 may notify medical personnel to certain conditions by the XR headset(s) 920, display 34 and/or light indicator 28. The XR headset(s) 920 are each configured to display images on a see-through display screen to form an extended reality image that is overlaid on real-world objects viewable through the see-through display screen. Medical personnel may be prompted by surgical robot 4 to select a function, mode, and/or assess the condition of surgical system 2. Depressing secondary button a single time may activate certain functions, modes, and/or acknowledge information communicated to medical personnel through the XR headset(s) 920, display 34 and/or light indicator 28. Additionally, depressing the secondary button multiple times in rapid succession may activate additional functions, modes, and/or select information communicated to medical personnel through the XR headset(s) 920, display 34 and/or light indicator 28.

With further reference to FIG. 8, electrical components of the surgical robot 4 include platform subsystem 802, computer subsystem 820, motion control subsystem 840, and tracking subsystem 830. Platform subsystem 802 includes battery 806, power distribution module 804, connector panel 808, and charging station 810. Computer subsystem 820 includes computer 822, display 824, and speaker 826. Motion control subsystem 840 includes driver circuit 842, motors 850, 851, 852, 853, 854, stabilizers 855, 856, 857, 858, end effector connector 844, and controller 846. Tracking subsystem 830 includes position sensor 832 and camera converter 834. Surgical robot 4 may also include a removable foot pedal 880 and removable tablet computer 890.

Input power is supplied to surgical robot 4 via a power source which may be provided to power distribution module 804. Power distribution module 804 receives input power and is configured to generate different power supply voltages that are provided to other modules, components, and subsystems of surgical robot 4. Power distribution module 804 may be configured to provide different voltage supplies to connector panel 808, which may be provided to other components such as computer 822, display 824, speaker 826, driver 842 to, for example, power motors 850-854 and end effector coupler 844, and provided to camera converter 834 and other components for surgical robot 4. Power distribution module 804 may also be connected to battery 806, which serves as temporary power source in the event that power distribution module 804 does not receive power from an input power. At other times, power distribution module 804 may serve to charge battery 806.

Connector panel 808 may serve to connect different devices and components to surgical robot 4 and/or associated components and modules. Connector panel 808 may contain one or more ports that receive lines or connections from different components. For example, connector panel 808 may have a ground terminal port that may ground surgical robot 4 to other equipment, a port to connect foot pedal 880, a port to connect to tracking subsystem 830, which may include position sensor 832, camera converter 834, and DRA tracking cameras 870. Connector panel 808 may also include other ports to allow USB, Ethernet, HDMI communications to other components, such as computer 822. In accordance with some embodiments, the connector panel 808 can include a wired and/or wireless interface for operatively connecting one or more XR headsets 920 to the tracking subsystem 830 and/or the computer subsystem 820.

Control panel 816 may provide various buttons or indicators that control operation of surgical robot 4 and/or provide information from surgical robot 4 for observation by an operator. For example, control panel 816 may include buttons to power on or off surgical robot 4, lift or lower vertical column 16, and lift or lower stabilizers 855-858 that may be designed to engage casters 12 to lock surgical robot 4 from physically moving. Other buttons may stop surgical robot 4 in the event of an emergency, which may remove all motor power and apply mechanical brakes to stop all motion from occurring. Control panel 816 may also have indicators notifying the operator of certain system conditions such as a line power indicator or status of charge for battery 806. In accordance with some embodiments, one or more XR headsets 920 may communicate, e.g. via the connector panel 808, to control operation of the surgical robot 4 and/or to received and display information generated by surgical robot 4 for observation by persons wearing the XR headsets 920.

Computer 822 of computer subsystem 820 includes an operating system and software to operate assigned functions of surgical robot 4. Computer 822 may receive and process information from other components (for example, tracking subsystem 830, platform subsystem 802, and/or motion control subsystem 840) in order to display information to the operator. Further, computer subsystem 820 may provide output through the speaker 826 for the operator. The speaker may be part of the surgical robot, part of an XR headset 920, or within another component of the surgical system 2. The display 824 may correspond to the display 34 shown in FIGS. 1 and 2.

Tracking subsystem 830 may include position sensor 832 and camera converter 834. Tracking subsystem 830 may correspond to the camera tracking system component 6 of FIG. 3. The DRA tracking cameras 870 operate with the position sensor 832 to determine the pose of DRAs 52. This tracking may be conducted in a manner consistent with the present disclosure including the use of infrared or visible light technology that tracks the location of active or passive elements of DRAs 52, such as LEDs or reflective markers, respectively.

Functional operations of the tracking subsystem 830 and the computer subsystem 820 can be included in the computer platform 910, which can be transported by the camera tracking system component 6′ of FIGS. 3A and 3B. The tracking subsystem 830 can be configured to determine the poses, e.g., location and angular orientation of the tracked DRAs. The computer platform 910 can also include a navigation controller that is configured to use the determined poses to provide navigation information to users that guides their movement of tracked tools relative to position-registered patient images and/or tracked anatomical structures during a planned surgical procedure. The computer platform 910 can display information on the display of FIGS. 3B and 3C and/or to one or more XR headsets 920. The computer platform 910, when used with a surgical robot, can be configured to communicate with the computer subsystem 820 and other subsystems of FIG. 8 to control movement of the end effector 26. For example, as will be explained below the computer platform 910 can generate a graphical representation of a patient's anatomical structure, surgical tool, user's hand, etc. with a displayed size, shape, color, and/or pose that is controlled based on the determined pose(s) of one or more the tracked DRAs, and which the graphical representation that is displayed can be dynamically modified to track changes in the determined poses over time.

Motion control subsystem 840 may be configured to physically move vertical column 16, upper arm 18, lower arm 20, or rotate end effector coupler 22. The physical movement may be conducted through the use of one or more motors 850-854. For example, motor 850 may be configured to vertically lift or lower vertical column 16. Motor 851 may be configured to laterally move upper arm 18 around a point of engagement with vertical column 16 as shown in FIG. 2. Motor 852 may be configured to laterally move lower arm 20 around a point of engagement with upper arm 18 as shown in FIG. 2. Motors 853 and 854 may be configured to move end effector coupler 22 to provide translational movement and rotation along in about three-dimensional axes. The computer platform 910 shown in FIG. 9 can provide control input to the controller 846 that guides movement of the end effector coupler 22 to position a passive end effector, which is connected thereto, with a planned pose (i.e., location and angular orientation relative to defined 3D orthogonal reference axes) relative to an anatomical structure that is to be operated on during a planned surgical procedure. Motion control subsystem 840 may be configured to measure position of the end effector coupler 22 and/or the end effector 26 using integrated position sensors (e.g. encoders).

FIG. 9 illustrates a block diagram of components of a surgical system that includes imaging devices (e.g., C-Arm 104, O-Arm 106, etc.) connected to a computer platform 910 which can be operationally connected to a camera tracking system component 6 (FIG. 3A) or 6′ (FIGS. 3B,3C) and/or to surgical robot 4 according to some embodiments of the present disclosure. Alternatively, at least some operations disclosed herein as being performed by the computer platform 910 may additionally or alternatively be performed by components of a surgical system.

Referring to FIG. 9, the computer platform 910 includes a display 912, at least one processor circuit 914 (also referred to as a processor for brevity), at least one memory circuit 916 (also referred to as a memory for brevity) containing computer readable program code 918, and at least one network interface 902 (also referred to as a network interface for brevity). The display 912 may be part of an XR headset 920 in accordance with some embodiments of the present disclosure. The network interface 902 can be configured to connect to a C-Arm imaging device 104 in FIG. 10, an O-Arm imaging device 106 in FIG. 11, another medical imaging device, an image database 950 containing patient medical images, components of the surgical robot 4, and/or other electronic equipment.

When used with a surgical robot 4, the display 912 may correspond to the display 34 of FIG. 2 and/or the tablet 890 of FIG. 8 and/or the XR headset 920 that is operatively connected to the surgical robot 4, the network interface 902 may correspond to the platform network interface 812 of FIG. 8, and the processor 914 may correspond to the computer 822 of FIG. 8. The network interface 902 of the XR headset 920 may be configured to communicate through a wired network, e.g., thin wire ethernet, and/or through wireless RF transceiver link according to one or more wireless communication protocols, e.g., WLAN, 3GPP 4G and/or 5G (New Radio) cellular communication standards, etc.

The processor 914 may include one or more data processing circuits, such as a general purpose and/or special purpose processor, e.g., microprocessor and/or digital signal processor. The processor 914 is configured to execute the computer readable program code 918 in the memory 916 to perform operations, which may include some or all of the operations described herein as being performed for surgery planning, navigated surgery, and/or robotic surgery.

The computer platform 910 can be configured to provide surgery planning functionality. The processor 914 can operate to display on the display device 912 and/or on the XR headset 920 an image of an anatomical structure, e.g., vertebra, that is received from one of the imaging devices 104 and 106 and/or from the image database 950 through the network interface 920. The processor 914 receives an operator's definition of where the anatomical structure shown in one or more images is to have a surgical procedure, e.g., screw placement, such as by the operator touch selecting locations on the display 912 for planned procedures or using a mouse-based cursor to define locations for planned procedures. When the image is displayed in the XR headset 920, the XR headset can be configured to sense in gesture-based commands formed by the wearer and/or sense voice based commands spoken by the wearer, which can be used to control selection among menu items and/or control how objects are displayed on the XR headset 920 as will be explained in further detail below.

The computer platform 910 can be configured to enable anatomy measurement, which can be particularly useful for knee surgery, like measurement of various angles determining center of hip, center of angles, natural landmarks (e.g. transepicondylar line, Whitesides line, posterior condylar line), etc. Some measurements can be automatic while some others can involve human input or assistance. The computer platform 910 may be configured to allow an operator to input a choice of the correct implant for a patient, including choice of size and alignment. The computer platform 910 may be configured to perform automatic or semi-automatic (involving human input) segmentation (image processing) for CT images or other medical images. The surgical plan for a patient may be stored in a cloud-based server, which may correspond to database 950, for retrieval by the surgical robot 4.

During orthopedic surgery, for example, a surgeon may choose which cut to make (e.g. posterior femur, proximal tibia etc.) using a computer screen (e.g. touchscreen) or extended reality (XR) interaction (e.g., hand gesture based commands and/or voice based commands) via, e.g., the XR headset 920. The computer platform 910 can generate navigation information which provides visual guidance to the surgeon for performing the surgical procedure. When used with the surgical robot 4, the computer platform 910 can provide guidance that allows the surgical robot 4 to automatically move the end effector 26 to a target pose so that the surgical tool is aligned with a target location to perform the surgical procedure on an anatomical structure.

In some embodiments, the surgical system 900 can use two DRAs to track patient anatomy position, such as one connected to patient tibia and one connected to patient femur. The system 900 may use standard navigated instruments for the registration and checks (e.g. a pointer similar to the one used in Globus ExcelsiusGPS system for spine surgery).

A particularly challenging task in navigated surgery is how to plan the position of an implant in spine, knee, and other anatomical structures where surgeons struggle to perform the task on a computer screen which is a 2D representation of the 3D anatomical structure. The system 900 could address this problem by using the XR headset 920 to display a three-dimensional (3D) computer generated representations of the anatomical structure and a candidate implant device. The computer generated representations are scaled and posed relative to each other on the display screen under guidance of the computer platform 910 and which can be manipulated by a surgeon while viewed through the XR headset 920. A surgeon may, for example, manipulate the displayed computer-generated representations of the anatomical structure, the implant, a surgical tool, etc., using hand gesture based commands and/or voice based commands that are sensed by the XR headset 920.

For example, a surgeon can view a displayed virtual handle on a virtual implant, and can manipulate (e.g., grab and move) the virtual handle to move the virtual implant to a desired pose and adjust a planned implant placement relative to a graphical representation of an anatomical structure. Afterward, during surgery, the computer platform 910 could display navigation information through the XR headset 920 that facilitates the surgeon's ability to more accurately follow the surgical plan to insert the implant and/or to perform another surgical procedure on the anatomical structure. When the surgical procedure involves bone removal, the progress of bone removal, e.g., depth of cut, can be displayed in real-time through the XR headset 920. Other features that may be displayed through the XR headset 920 can include, without limitation, gap or ligament balance along a range of joint motion, contact line on the implant along the range of joint motion, ligament tension and/or laxity through color or other graphical renderings, etc.

The computer platform 910, in some embodiments, can allow planning for use of standard surgical tools and/or implants, e.g., posterior stabilized implants and cruciate retaining implants, cemented and cementless implants, revision systems for surgeries related to, for example, total or partial knee and/or hip replacement and/or trauma.

An automated imaging system can be used in conjunction with the computer platform 910 to acquire pre-operative, intra-operative, post-operative, and/or real-time image data of an anatomical structure. Example automated imaging systems are illustrated in FIGS. 10 and 11. In some embodiments, the automated imaging system is a C-arm 104 (FIG. 10) imaging device or an O-arm® 106 (FIG. 11). (O-arm® is copyrighted by Medtronic Navigation, Inc. having a place of business in Louisville, Colo., USA). It may be desirable to take x-rays of a patient from a number of different positions, without the need for frequent manual repositioning of the patient which may be required in an x-ray system. C-arm 104 x-ray diagnostic equipment may solve the problems of frequent manual repositioning and may be well known in the medical art of surgical and other interventional procedures. As illustrated in FIG. 10, a C-arm includes an elongated C-shaped member terminating in opposing distal ends 112 of the “C” shape. C-shaped member is attached to an x-ray source 114 and an image receptor 116. The space within C-arm 104 of the arm provides room for the physician to attend to the patient substantially free of interference from the x-ray support structure.

The C-arm is mounted to enable rotational movement of the arm in two degrees of freedom, (i.e. about two perpendicular axes in a spherical motion). C-arm is slidably mounted to an x-ray support structure, which allows orbiting rotational movement of the C-arm about its center of curvature, which may permit selective orientation of x-ray source 114 and image receptor 116 vertically and/or horizontally. The C-arm may also be laterally rotatable, (i.e. in a perpendicular direction relative to the orbiting direction to enable selectively adjustable positioning of x-ray source 114 and image receptor 116 relative to both the width and length of the patient). Spherically rotational aspects of the C-arm apparatus allow physicians to take x-rays of the patient at an optimal angle as determined with respect to the particular anatomical condition being imaged.

The O-arm® 106 illustrated in FIG. 11 includes a gantry housing 124 which may enclose an image capturing portion, not illustrated. The image capturing portion includes an x-ray source and/or emission portion and an x-ray receiving and/or image receiving portion, which may be disposed about one hundred and eighty degrees from each other and mounted on a rotor (not illustrated) relative to a track of the image capturing portion. The image capturing portion may be operable to rotate three hundred and sixty degrees during image acquisition. The image capturing portion may rotate around a central point and/or axis, allowing image data of the patient to be acquired from multiple directions or in multiple planes.

The O-arm® 106 with the gantry housing 124 has a central opening for positioning around an object to be imaged, a source of radiation that is rotatable around the interior of gantry housing 124, which may be adapted to project radiation from a plurality of different projection angles. A detector system is adapted to detect the radiation at each projection angle to acquire object images from multiple projection planes in a quasi-simultaneous manner. The gantry may be attached to a support structure O-arm® support structure, such as a wheeled mobile cart with wheels, in a cantilevered fashion. A positioning unit translates and/or tilts the gantry to a planned position and orientation, preferably under control of a computerized motion control system. The gantry may include a source and detector disposed opposite one another on the gantry. The source and detector may be secured to a motorized rotor, which may rotate the source and detector around the interior of the gantry in coordination with one another. The source may be pulsed at multiple positions and orientations over a partial and/or full three hundred and sixty degree rotation for multi-planar imaging of a targeted object located inside the gantry. The gantry may further comprise a rail and bearing system for guiding the rotor as it rotates, which may carry the source and detector. Both and/or either O-arm® 106 and C-arm 104 may be used as automated imaging system to scan a patient and send information to the surgical system 2.

Images captured by an imaging system can be displayed on the XR headset 920 and/or another display device of the computer platform 910, the surgical robot 4, and/or another component of the surgical system 900. The XR headset 920 may be connected to one or more of the imaging devices 104 and/or 106 and/or to the image database 950, e.g., via the computer platform 910, to display images therefrom. A user may provide control inputs through the XR headset 920, e.g., gesture and/or voice based commands, to control operation of one or more of the imaging devices 104 and/or 106 and/or the image database 950.

FIG. 12 illustrates a block diagram view of the components of a surgical system that include a pair of XR headsets 1200 and 1210 (head-mounted displays HMD1 and HMD2), which may correspond to the XR headset 920 shown in FIG. 13 and operate in accordance with some embodiments of the present disclosure.

Referring to the example scenario of FIG. 12, the assistant 612 and surgeon 610 are both wearing the XR headsets 1210 and 1210, respectively. It is optional for the assistant 612 to wear the XR headset 1210. The XR headsets 1200 and 1210 are configured to provide an interactive environment through which the wearers can view and interact with information related to a surgical procedure as will be described further below. This interactive XR based environment may eliminate a need for the tech personnel 614 to be present in the operating room and may eliminate a need for use of the display 34 shown in FIG. 6. Each XR headset 1200 and 1210 can include one or more cameras that are be configured to provide an additional source of tracking of DRAs or other reference arrays attached to instruments, an anatomical structure, the end effector 26, and/or other equipment. In the example of FIG. 12, XR headset 1200 has a field-of-view (FOV) 1202 for tracking DRAs and other objects, XR headset 1210 has a FOV 1212 partially overlapping FOV 1202 for tracking DRAs and other objects, and the tracking cameras 46 has another FOV 600 partially overlapping FOVs 1202 and 1212 for tracking DRAs and other objects.

If one or more cameras is obstructed from viewing a DRA attached to a tracked object, e.g., a surgical instrument, but the DRA is in view of one or more other cameras the tracking subsystem 830 and/or navigation controller 828 can continue to track the object seamlessly without loss of navigation. Additionally, if there is partial occlusion of the DRA from the perspective of one camera, but the entire DRA is visible via multiple camera sources, the tracking inputs of the cameras can be merged to continue navigation of the DRA. One of the XR headsets and/or the tracking cameras 46 may view and track the DRA on another one of the XR headsets to enable the computer platform 910 (FIGS. 9 and 14), the tracking subsystem 830, and/or another computing component to determine the pose of the DRA relative to one or more defined coordinate systems, e.g., of the XR headsets 1200/1210, the tracking cameras 46, and/or another coordinate system defined for the patient, table, and/or room.

The XR headsets 1200 and 1210 can be operatively connected to view video, pictures, and/or other information received from and/or to provide commands that control various equipment in the surgical room, including but not limited to neuromonitoring, microscopes, video cameras, and anesthesia systems. Data from the various equipment may be processed and displayed within the headset, for example the display of patient vitals or the microscope feed.

Example XR Headset Components and Integration to Navigated Surgery, Surgical Robots, and Other Equipment

FIG. 13 illustrates an XR headset 920 which is configured in accordance with some embodiments of the present disclosure. The XR headset includes a headband 1306 configured to secure the XR headset to a wearer's head, an electronic component enclosure 1304 supported by the headband 1306, and a display screen 1302 that extends laterally across and downward from the electronic component enclosure 1304. The display screen 1302 may be a see-through LCD display device or a semi-reflective lens that reflects images projected by a display device toward the wearer's eyes. A set of DRA fiducials, e.g., dots are painted or attached in a spaced apart known arranged on one or both sides of the headset. The DRA on the headset enables the tracking cameras on the auxiliary tracking bar to track pose of the headset 920 and/or enables another XR headset to track pose of the headset 920.

The display screen 1302 operates as a see-through display screen, also referred to as a combiner, that reflects light from display panels of a display device toward the user's eyes. The display panels can be located between the electronic component enclosure and the user's head, and angled to project virtual content toward the display screen 1302 for reflection toward the user's eyes. The display screen 1302 is semi-transparent and semi-reflective allowing the user to see reflected virtual content superimposed on the user's view of a real-world scene. The display screen 1302 may have different opacity regions, such as the illustrated upper laterally band which has a higher opacity than the lower laterally band. Opacity of the display screen 1302 may be electronically controlled to regulate how much light from the real-world scene passes through to the user's eyes. A high opacity configuration of the display screen 1302 results in high-contrast virtual images overlaid on a dim view of the real-world scene. A low opacity configuration of the display screen 1302 can result in more faint virtual images overlaid on a clearer view of the real-world scene. The opacity may be controlled by applying an opaque material on a surface of the display screen 1302.

According to some embodiments the surgical system includes an XR headset 920 and an XR headset controller, e.g., controller 1430 in FIG. 14 or controller 3410 in FIG. 34. The XR headset 920 is configured to be worn by a user during a surgical procedure and has a see-through display screen 1302 that is configured to display an XR image and to allow at least a portion of a real-world scene to pass therethrough for viewing by the user. The XR headset 920 also includes an opacity filter positioned between at least one of the user's eyes and the real-world scene when the see-through display screen 1302 is viewed by the user. The opacity filter is configured to provide opaqueness to light from the real-world scene. The XR headset controller is configured to communicate with a navigation controller, e.g., controller(s) 828A, 828B, and/or 828C in FIG. 14, to receive navigation information from the navigation controller which provides guidance to the user during the surgical procedure on an anatomical structure, and is further configured to generate the XR image based on the navigation information for display on the see-through display screen 1302.

Opacity of the display screen 1302 may be configured as a gradient having a more continuously changing opacity with distance downward from a top portion of the display screen 1302. The gradient's darkest point can be located at the top portion of the display screen 1302, and gradually becoming less opaque further down on the display screen 1302 until the opacity is transparent or not present. In an example further embodiment, the gradient can change from about 90% opacity to entirely transparent approximately at the mid-eye level of the display screen 1302. With the headset properly calibrated and positioned, the mid-eye level can correspond to the point where the user would look straight out, and the end of the gradient would be located at the “horizon” line of the eye. The darker portion of the gradient will allow crisp, clear visuals of the virtual content and help to block the intrusive brightness of the overhead operating room lights.

Using an opacity filter in this manner enables the XR headset 920 to provide virtual reality (VR) capabilities, by substantially or entirely blocking light from the real-world scene, along an upper portion of the display screen 1302 and to provide AR capabilities along a middle or lower portion of the display screen 1302. This allows the user to have the semi-translucence of AR where needed and allowing clear optics of the patient anatomy during procedures. Configuring the display screen 1302 as a gradient instead of as a more constant opacity band can enable the wearer to experience a more natural transition between a more VR type view to a more AR type view without experiencing abrupt changes in brightness of the real-world scene and depth of view that may otherwise strain the eyes such as during more rapid shifting between upward and downward views.

The display panels and display screen 1302 can be configured to provide a wide field of view see-through XR display system. In one example configuration they provide an 80° diagonal field-of-view (FOV) with 55° of vertical coverage for a user to view virtual content. Other diagonal FOV angles and vertical coverage angles can be provided through different size display panels, different curvature lens, and/or different distances and angular orientations between the display panels and curved display screen 1302.

FIG. 14 illustrates electrical components of the XR headset 920 that can be operatively connected to the computer platform 910, to one or more of the imaging devices, such as the C-arm imaging device 104, the O-arm imaging device 106, and/or the image database 950, and/or to the surgical robot 800 in accordance with various embodiments of the present disclosure.

The XR headset 920 provides an improved human interface for performing navigated surgical procedures. The XR headset 920 can be configured to provide functionalities, e.g., via the computer platform 910, that include without limitation any one or more of: identification of hand gesture based commands and/or voice based commands, display XR graphical objects on a display device 1450. The display device 1450 may a video projector, flat panel display, etc., which projects the displayed XR graphical objects on the display screen 1302. The user can view the XR graphical objects as an overlay anchored to particular real-world objects viewed through the display screen 1302 (FIG. 13). The XR headset 920 may additionally or alternatively be configured to display on the display screen 1450 video feeds from cameras mounted to one or more XR headsets 920 and other cameras.

Electrical components of the XR headset 920 can include a plurality of cameras 1440, a microphone 1442, a gesture sensor 1444, a pose sensor (e.g., inertial measurement unit (IMU)) 1446, a display module 1448 containing the display device 1450, and a wireless/wired communication interface 1452. As will be explained below, the cameras 1440 of the XR headset may be visible light capturing cameras, near infrared capturing cameras, or a combination of both.

The cameras 1440 may be configured operate as the gesture sensor 1444 by capturing for identification user hand gestures performed within the field of view of the camera(s) 1440. Alternatively the gesture sensor 1444 may be a proximity sensor and/or a touch sensor that senses hand gestures performed proximately to the gesture sensor 1444 and/or senses physical contact, e.g. tapping on the sensor or the enclosure 1304. The pose sensor 1446, e.g., IMU, may include a multi-axis accelerometer, a tilt sensor, and/or another sensor that can sense rotation and/or acceleration of the XR headset 920 along one or more defined coordinate axes. Some or all of these electrical components may be contained in the component enclosure 1304 or may be contained in another enclosure configured to be worn elsewhere, such as on the hip or shoulder.

As explained above, the surgical system 2 includes a camera tracking system component 6/6′ and a tracking subsystem 830 which may be part of the computer platform 910. The surgical system may include imaging devices (e.g., C-arm 104, O-arm 106, and/or image database 950) and/or a surgical robot 4. The tracking subsystem 830 is configured to determine a pose of DRAs attached to an anatomical structure, an end effector, a surgical tool, etc. A navigation controller 828 is configured to determine a target pose for the surgical tool relative to an anatomical structure based on a surgical plan, e.g., from a surgical planning function performed by the computer platform 910 of FIG. 9, defining where a surgical procedure is to be performed using the surgical tool on the anatomical structure and based on a pose of the anatomical structure determined by the tracking subsystem 830. The navigation controller 828 may be further configured to generate steering information based on the target pose for the surgical tool, the pose of the anatomical structure, and the pose of the surgical tool and/or the end effector, where the steering information indicates where the surgical tool and/or the end effector of a surgical robot should be moved to perform the surgical plan.

The electrical components of the XR headset 920 can be operatively connected to the electrical components of the computer platform 910 through a wired/wireless interface 1452. The electrical components of the XR headset 920 may be operatively connected, e.g., through the computer platform 910 or directly connected, to various imaging devices, e.g., the C-arm imaging device 104, the I/O-arm imaging device 106, the image database 950, and/or to other medical equipment through the wired/wireless interface 1452.

The surgical system 2 further includes at least one XR headset controller 1430 (also referred to as “XR headset controller” for brevity) that may reside in the XR headset 920, the computer platform 910, and/or in another system component connected via wired cables and/or wireless communication links. Various functionality is provided by software executed by the XR headset controller 1430. The XR headset controller 1430 is configured to receive navigation information from the navigation controller 828 which provides guidance to the user during the surgical procedure on an anatomical structure, and is configured to generate an XR image based on the navigation information for display on the display device 1450 for projection on the see-through display screen 1302.

The configuration of the display device 1450 relative to the display screen (also referred to as “see-through display screen”) 1302 is configured to display XR images in a manner such that when the user wearing the XR headset 920 looks through the display screen 1302 the XR images appear to be in the real world. The display screen 1302 can be positioned by the headband 1306 in front of the user's eyes.

The XR headset controller 1430 can be within a housing that is configured to be worn on a user's head or elsewhere on the user's body while viewing the display screen 1302 or may be remotely located from the user viewing the display screen 1302 while being communicatively connected to the display screen 1302. The XR headset controller 1430 can be configured to operationally process signaling from the cameras 1440, the microphone 142, and/or the pose sensor 1446, and is connected to display XR images on the display device 1450 for user viewing on the display screen 1302. Thus, the XR headset controller 1430 illustrated as a circuit block within the XR headset 920 is to be understood as being operationally connected to other illustrated components of the XR headset 920 but not necessarily residing within a common housing (e.g., the electronic component enclosure 1304 of FIG. 13) or being otherwise transportable by the user. For example, the XR headset controller 1430 may reside within the computer platform 910 which, in turn, may reside within a housing of the computer tracking system component 6′ shown in FIGS. 3B and 3C.

Example XR Headset Component Optical Arrangement

FIG. 34 illustrates a block diagram showing arrange of optical components of the XR headset 920 in accordance with some embodiments of the present disclosure. Referring to FIG. 34, the display device 1450 is configured to display XR images generated by the XR headset controller 1430, light from which is projected as XR images 1450 toward the display screen 1302. The display screen 1302 is configured to combine light of the XR images 1450 and light from the real-world scene 1502 into a combined augmented view 1504 that is directed to the user's eye(s) 1510. The display screen 1302 configured in this manner operates as a see-through display screen. The XR headset 920 can include any plural number of tracking cameras 1440. The cameras 1440 may be visible light capturing cameras, near infrared capturing cameras, or a combination of both.

Example User Views through the XR Headset

The XR headset operations can display both 2D images and 3D models on the display screen 1302. The 2D images may preferably be displayed in a more opaque band of the display screen 1302 (upper band) and the 3D model may be more preferably displayed in the more transparent band of the display screen 1302, otherwise known as the environmental region (bottom band). Below the lower band where the display screen 1302 ends the wearer has an unobstructed view of the surgical room. It is noted that where XR content is display on the display screen 1302 may be fluidic. It is possible that where the 3D content is displayed moves to the opaque band depending on the position of the headset relative to the content, and where 2D content is displayed can be placed in the transparent band and stabilized to the real world. Additionally, the entire display screen 1302 may be darkened under electronic control to convert the headset into virtual reality for surgical planning or completely transparent during the medical procedure. As explained above, the XR headset 920 and associated operations not only support navigated procedures, but also can be performed in conjunction with robotically assisted procedures.

FIG. 16 illustrates an example view through the display screen 1302 of the XR headset 920 for providing navigation assistance to a user who is manipulating a surgical tool 1602 during a medical procedure in accordance with some embodiments of the present disclosure. Referring to FIG. 16, when the surgical tool 1602 is brought in vicinity of a tracked anatomical structure so that dynamic reference arrays 1630 and 1632, connected to the surgical tool 1602, become within the field of view of the cameras 1440 (FIG. 15) and/or 46 (FIG. 6), a graphical representation 1600 of the tool can be displayed in 2D and/or 3D images in relation to a graphical representation 1610 of the anatomical structure. The user can use the viewed graphical representations to adjust a trajectory 1620 of the surgical tool 1602, which can be illustrated as extending from the graphical representation 2000 of the tool through the graphical representation 1610 of the anatomical structure. The XR headset 920 may also display textual information and other objects 1640. The dashed line 1650 extending across the viewed display screen represents an example division between different opacity level upper and lower bands.

Other types of XR images (virtual content) that can be displayed on the display screen 1302 can include, but are not limited to any one or more of:

-   -   I) 2D Axial, Sagittal and/or Coronal views of patient anatomy;     -   2) overlay of planned vs currently tracked tool and surgical         implant locations;     -   3) gallery of preoperative images;     -   4) video feeds from microscopes and other similar systems or         remote video conferencing;     -   5) options and configuration settings and buttons;     -   6) floating 3D models of patient anatomy with surgical planning         information;     -   7) real-time tracking of surgical instruments relative to         floating patient anatomy;     -   8) augmented overlay of patient anatomy with instructions and         guidance; and     -   9) augmented overlay of surgical equipment.

Example Configuration of Cameras for Tracking System Component

FIG. 17 illustrates example configuration of an auxiliary tracking bar 46 having two pairs of stereo tracking cameras configured in accordance with some embodiments of the present disclosure. The auxiliary tracking bar 46 is part of the camera tracking system component of FIGS. 3A, 3B, and 3C. The stereo tracking cameras include a stereo pair of spaced apart visible light capturing cameras and another stereo pair of spaced apart near infrared capturing cameras, in accordance with one embodiment. Alternatively, only one stereo pair of visible light capturing cameras or only one stereo pair of near infrared capture cameras can used in the auxiliary tracking bar 46. Any plural number of near infrared and/or visible light cameras can be used.

Pose Measurement Chaining

As explained above, navigated surgery can include computer vision tracking and determination of pose (e.g., position and orientation in a six degree-of-freedom coordinate system) of surgical instruments, such as by determining pose of attached DRAs that include spaced apart fiducials, e.g., disks or spheres, arranged in a known manner. The computer vision uses spaced apart tracking cameras, e.g., stereo cameras, that are configured to capture near infrared and/or visible light. In this scenario, there are three parameters jointly competing for optimization: (1) accuracy, (2) robustness, and (3) user ergonomics during a surgical procedure.

Some further aspects of the present disclosure are directed to computer operations that combine (chain) measured poses in ways that can improve optimization of one or more of the above three parameters by incorporating additional tracking cameras mounted to one or more XR headsets. As shown in FIG. 17, a stereo pair of visible light tracking cameras and another stereo pair of near infrared tracking cameras can be attached to the auxiliary tracking bar of the camera tracking system component in accordance with some embodiments of the present disclosure. Operational algorithms are disclosed that analyze the pose of DRAs that are fully observed or partially observed (e.g., when less than all of the fiducials of a DRA are viewed by a pair of stereo cameras), and combine the observed poses or partial poses in ways that can improve accuracy, robustness, and/or ergonomics during navigated surgery.

As explained above, the XR headset may be configured to augment a real-world scene with computer generated XR images. The XR headset may be configured to provide an XR viewing environment by displaying the computer generated XR images on a see-through display screen that allows light from the real-world scene to pass therethrough for combined viewing by the user. Alternatively, the XR headset may be configured to provide a VR viewing environment by preventing or substantially preventing light from the real-world scene from being directly viewed by the user along the viewing path of the displayed XR images. An XR headset can be configured to provide both AR and VR viewing environments. In one embodiment, both AR and VR viewing environments are provided by lateral bands of substantially differing opacity arranged between the see-through display screen and the real-world scene, so that a VR viewing environment is provided for XR images aligned with a high opacity band and an AR viewing environment is provided for XR images aligned with the low opacity band. In another embodiment, both AR and VR viewing environments are provided by computer adjustable control of an opacity filter that variably constrains how much light from the real-world scene passes through a see-through display screen for combining with the XR images viewed by the user. Thus, the XR headset can also be referred to as an AR headset or a VR headset.

As was also explained above, the XR headset can include near infrared tracking cameras and/or visible light tracking cameras that are configured to track fiducials of DRAs connected to surgical instruments, patient anatomy, other XR headset(s), and/or a robotic end effector. Using near infrared tracking and/or visible light tracking on the XR headset provides additional tracking volume coverage beyond what cameras on a single auxiliary tracking bar can provide. Adding near infrared tracking cameras to the existing auxiliary tracking bar allows for the headset location to be tracked more robustly but less accurately than in visible light. Mechanically calibrating the visible and near infrared tracking coordinate systems enables the coordinate systems to be aligned sufficiently to perform 3D DRA fiducials triangulation operations using stereo matching to jointly identify pose of the DRA fiducials between the visible and near infrared tracking coordinate systems. Using both visible and near infrared tracking coordinate systems can enable any one or more of: (a) identifying tools that would not be identified using a single coordinate system; (b) increased pose tracking accuracy; (c) enabling a wider range of motion without losing tracking of surgical instruments, patient anatomy, and/or a robotic end effector; and (d) naturally track an XR headset in the same coordinate system as the navigated surgical instruments.

FIG. 18 illustrates a block diagram view of the components of a surgical system that include tracking cameras in a pair of XR headsets 1200 and 1210 (head-mounted displays HMD1 and HMD2) and tracking cameras in a camera tracking bar in the camera tracking system component 6′ which houses the computer platform 910. The computer platform 910 can include the tracking subsystem 830, the navigation controller 828, and the XR headset controller 1430 as was earlier shown in FIG. 14.

Referring to the surgical system of FIG. 18, a surgeon and an assistant are both wearing XR headsets HMD1 1200 and HMD2 1210, respectively, each if which includes tracking cameras that may be configured as shown in FIG. 13. It is optional for the assistant to wear the XR headset HMD2 1210.

The combination of XR headsets HMD1 1200 and HMD2 1210 and the tracking cameras 46 on the auxiliary tracking bar can, in operation with the computer platform 910, more robustly track the example objects of a patient reference array (R), robotic end effector (E), and surgical tool (T) or instrument. The overlapping views from different perspectives that are provided by the XR headsets HMD1 1200 and HMD2 1210 and the tracking cameras 46 on the auxiliary tracking bar are shown in FIG. 12.

Each of the items labeled in FIG. 18 represent a unique coordinate system. Descriptions of the coordinate system labels are as follows:

-   -   A=visible light coordinate system of second headset HMD2 1210;     -   N3=NIR coordinate system of second headset HMD2 1210;     -   S=visible light coordinate system of primary headset HMD1 1200;     -   N2=NIR coordinate system of the primary headset HMD1 1200;     -   N=NIR coordinate system of the auxiliary navigation bar 46;     -   V=visible light coordinate system of the auxiliary navigation         bar 46;     -   R=NIR coordinate system of a patient reference fiducial array         602;     -   T=NIR coordinate system of a tracked tool 604;     -   E=NIR coordinate system of a tracked robot end effector on         robotic arm 20; and     -   W=Inertially navigated world coordinate system with stable         gravity vector.

The spatial relationships of some of these labeled objects (and by extension, coordinate systems) can be measured and calibrated during the manufacturing process, when the equipment is installed in an operating room, and/or before a surgical procedure is to be performed. In the disclosed system, the following coordinate systems are calibrated: T_(N2) ^(S); T_(N3) ^(A); T_(N) ^(V), where the term “T” is defined as a six degree-of-freedom (6 DOF) homogeneous transformation between the two indicated coordinates systems. Thus, for example, the term T_(N2) ^(S) is a 6 DOF homogeneous transformation between the visible light coordinate system of the primary headset HMD1 1200 and the NIR coordinate system of the primary headset HMD1 1200.

In one embodiment, the XR headsets HMD1 1200 and HMD2 1210 have passive visible light markers painted or otherwise attached to them (coordinate systems S and A), such as the DRA fiducials 1310 shown in FIG. 13. The tracking cameras are spatially calibrated to these passive fiducials (coordinate systems N2 and N3).

As explained above, the cameras on the XR headset HMD1 1200 and HMD2 1210 and the tracking cameras 46 on the auxiliary tracking bar have partially overlapping field of views. If one or more of the cameras on the XR headset HMD1 1200 are obstructed from viewing a DRA attached to a tracked object, e.g., a tracked tool (T), but the DRA is in view of the cameras of the other XR headset HMD2 1210 and/or the tracking cameras 46 on the auxiliary tracking bar, the computer platform 910 can continue to track the DRA seamlessly without loss of navigation. Additionally, if there is partial occlusion of the DRA from the perspective of the cameras on the XR headset HMD1 1200, but the entire DRA is visible via cameras of the other XR headset HMD2 1210 and/or the tracking cameras 46 on the auxiliary tracking bar, the tracking inputs of the cameras can be merged to continue navigation of the DRA.

More particularly, the various coordinate systems can be chained together by virtue of independent observations the various camera systems provided by the XR headsets HMD1 1200 and HMD2 1210 and the tracking cameras 46 on the auxiliary tracking bar. For example, each of the XR headsets HMD1 1200 and HMD2 1210 may require virtual augmentation of the robotic end effector (E). While one XR headset HMD1 1200 (N2) and the tracking cameras 46 on the auxiliary tracking bar (N) are able to see (E), perhaps the other XR headset HMD2 1210 (N3) cannot. The location of (E) with respect to (N3) can still be computed via one of several different operational methods. Operations according to one embodiment performing chaining of poses from a patient reference (R). If the patient reference (R) is seen by (N3) and either one of (N) or (N2), the pose of (E) with respect to (N3) can be solved directly by either one of the following two equations:

T _(N3) ^(E) =T _(N2) ^(E) T _(R) ^(N2) T _(N3) ^(R)—or—T _(N3) ^(E) =T _(N) ^(E) T _(R) ^(N) T _(N3) ^(R)

They key to this pose chaining is that the relationship between the frames at the end of each chain are inferred (circled and transported below). The chains can be arbitrarily long and are enabled by having more than one stereo camera system (e.g., N, N2, N3).

The camera tracking system can be configured to receive tracking information related to tracked objects from a first tracking camera (e.g., N3) and a second tracking camera (e.g., N2) during a surgical procedure. The camera tracking system can determine a first pose transform (e.g., T_(N3) ^(R)) between a first object (e.g., R) coordinate system and the first tracking camera (e.g., N3) coordinate system based on first object tracking information from the first tracking camera (e.g., N3) which indicates pose of the first object (e.g., R). The camera tracking system can determine a second pose transform (e.g., T_(R) ^(N2)) between the first object (e.g., R) coordinate system and the second tracking camera (e.g., N2) coordinate system based on first object tracking information from the second tracking camera (e.g., N2) which indicates pose of the first object (e.g., R). The camera tracking system can determine a third pose transform (e.g., T_(N2) ^(E)) between a second object (e.g., E) coordinate system and the second tracking camera (e.g., N2) coordinate system based on second object tracking information from the second tracking camera (e.g., N2) which indicates pose of the second object (e.g., E). The camera tracking system can determine a fourth pose transform (e.g., T_(N3) ^(E)) between the second object (e.g., E) coordinate system and the first tracking camera (e.g., N3) coordinate system based on combining the first, second, and third pose transforms.

In some further embodiments, the camera system can further determine pose of the second object (e.g., E) and the first tracking camera system (e.g., N3) coordinate system based on processing the tracking information through the fourth pose transform.

Because of the overlapping field of views of the various camera systems, the camera tracking system is capable of determining the pose of the second object (e.g., E) relative to first tracking camera (e.g., N3) when the first camera is blocked from seeing the second object (e.g., E). For example, in some embodiments the camera tracking system is further configured to determine the fourth pose transform (e.g., T_(N3) ^(E)) between the second object (e.g., E) coordinate system and the first tracking camera (e.g., N3) coordinate system without use of any tracking information from the first tracking camera (e.g., N3) indicating pose of the second object (e.g., E).

The camera tracking system can be further configured to determine pose of the second object (e.g., E) in the first tracking camera (e.g., N3) coordinate system based on processing through the fourth pose transform the tracking information from the first tracking camera (e.g., N3) which indicates pose of the first object (e.g., R), based on processing through the fourth pose transform (e.g., T_(N3) ^(E)) the tracking information from the second tracking camera (e.g., N2) which indicates pose of the first object (e.g., R), and based on processing through the fourth pose transform the tracking information from the second tracking camera (e.g., N2) which indicates pose of the second object (e.g., E).

Eye Tracking Using Inside-Out Cameras

In accordance with various further embodiments of the disclosure, an XR headset includes stereo tracking cameras used for inside-out tracking. The stereo tracking cameras are used to track the user's eyes and calibrate the headset to the eyes' (e.g., pupils') positions if there are two users facing each other or if a reflective surface is present.

Eye tracking systems normally use one to two inward facing cameras per eye to track where the eyes of a user wearing an XR headset are located and where the eyes are looking. In some embodiments, the eyes are tracked by their shape directly in visible light.

FIG. 19 illustrates an embodiment in which two users wearing XR headsets are facing each other and the camera tracking system uses the stereo tracking cameras on each XR headset to track the other user's eyes.

FIG. 22 illustrates a flow chart of operations performed by a camera tracking system for calibrating eye-to-XR headset displays and responsively controlling where symbols are displayed on XR headsets in accordance with some embodiments.

Referring to FIGS. 19 and 22, a camera tracking system operatively determines 2200 a first pose of a second extended-reality (XR) headset 1910 relative to stereo tracking cameras 1902 located on a first XR headset 1900 based on first tracking information from the stereo tracking cameras 1902. The camera tracking system determines 2202 a second pose of eyes of a user 1920 wearing the second XR headset 1910 relative to the stereo tracking cameras 1902 located on the first XR headset 1900 based on second tracking information from the stereo tracking cameras 1902. The camera tracking system also calibrates 2206 an eye-to-display relationship defining pose of the eyes 1914 of the user 1920 wearing the second XR headset 1910 to a display device of the second XR headset 1910 based on the determined first and second poses. The camera tracking system also controls 2208 where symbols are displayed on the display device of the second XR headset 1910 based on the eye-to-display relationship. This XR headset embodiment allows the tracking cameras 1902 on the first XR headset 1900 to track the pose of the second XR headset 1910 and the eyes 1914 of the user 1920 directly.

FIG. 24 illustrates a flow chart of operations performed by the camera tracking system for calibrating eye-to-XR headset displays of the other user (e.g. the user wearing the first XR headset) and responsively controlling where symbols are displayed on XR headsets in accordance with some embodiments.

Referring to FIG. 24, in a similar manner, the stereo tracking cameras 1912 on the second XR headset 1910 can be used to calibrate the eye-to-display relationship between the eyes 1904 of the user 1930 wearing the first XR headset 1900. More particularly, the camera tracking system operatively determines 2400 a third pose of a first XR headset 1900 relative to the stereo tracking cameras 1912 located on the second XR headset 1910 based on third tracking information from the stereo tracking cameras 1912. The camera tracking system determines 2402 a fourth pose of eyes 1904 of the user 1930 wearing the first XR headset 1900 relative to the stereo tracking cameras 1912 located on the second XR headset 1910 based on fourth tracking information from the stereo tracking cameras 1912. The camera tracking system also calibrates 2404 an eye-to-display relationship defining pose of the eyes 1904 of the user 1930 wearing the first XR headset 1900 to a display device of the first XR headset 1900 based on the determined third and fourth poses. The camera tracking system also controls 2206 where symbols are displayed on the display device of the first XR headset 1900 based on the eye-to-display relationship. This XR headset embodiment allows the tracking cameras 1912 on the second XR headset 1910 to track the pose of the first XR headset 1900 and the eyes 1904 of the user 1930 directly.

Some other embodiments include tracking markers located on the XR headset in order to improve robustness of headset pose estimation. In some embodiments, the first tracking information from the stereo tracking cameras 1902 on the first XR headset 1900 tracks a reference array on the second XR headset 1910. The second tracking information from the stereo tracking cameras 1902 tracks the eyes 1914 of the user wearing the second XR headset 1910. The XR headset-to-display transform relates the pose of the reference array on the second XR headset 1910 and the pose of the display device of the second XR headset 1910.

In some other embodiments, the determination of the first pose of the second XR headset 1910 relative to the stereo tracking cameras located on the first XR headset 1900, includes to determine first offset distances between the stereo tracking cameras 1902 located on the first XR headset 1900 and the second XR headset 1910. The determination of the second pose of the eyes 1914 of the user 1920 wearing the second XR headset 1910 relative to the stereo tracking cameras 1902 located on the first XR headset 1900, includes to determine second offset distances between the stereo tracking cameras 1902 located on the first XR headset 1900 and the eyes 1914 of the user 1920. The calibration of the eye-to-display relationship defining pose of the eyes 1914 of the user 1920 wearing the second XR headset 1910 to the display device of the second XR headset 1910, includes to determine third offset distances between the eyes 1914 of the user 1920 and the display device of the second XR headset 1910 based on the first and second offset distances.

Continuous tracking of the eyes 1914 of the user 1920 may thereby be achieved when there are two users 1920 and 1930 facing each other while respectively wearing the two headsets 1900 and 1910. The outward facing stereo tracking cameras 1902 will be able to track the other headset's pose as well as the other user's eyes 1914 relative to the headset being worn (while the two users are facing each other). One example of where this would happen regularly is in a surgery. A surgeon and a surgical assistant normally stand across the table from each other and face each other. If both are wearing headsets, the camera tracking system would be able to repetitively or continuously track the both person's headset and eyes.

In some embodiments, the determination of the second pose and the calibration of the eye-to-display relationship are performed responsive to detection of the eyes 1914 of the user 1920 wearing the second XR headset 1910 when imaged in video frames from the stereo tracking cameras 1902 located on the first XR headset 1900.

Accuracy of the pose determination from dynamic head tracking can be improved by time synchronizing the video streams between the stereo tracking cameras 1902 and 1912 on the respective XR headsets 1900 and 1910. The camera tracking system 910 can perform time synchronization of the video streams in several different embodiments. In one embodiment, each XR headset provides a synchronization signal which is used by the camera tracking system 910 to synchronize the video streams for purposes of object tracking. The synchronization signal may be transmitted through a wired or wireless connection with the video frames. The camera tracking system 910 may use the synchronization signals to estimate the time offset between the stereo tracking cameras 1902 and 1912 on the respective XR headsets 1900 and 1910. In another embodiments, the XR headsets 1900 and 1910 include a forward-facing light emitter apparatus (e.g., photo-diode/LED). The camera tracking system 910 can determine time offset between the stereo tracking cameras 1902 and 1912 based on time offset observed between when the light occurs the video frames. When determining pose of the XR headsets 1900 and 1910 and the user's eyes, the camera tracking system 910 can time align the video streams from the respective stereo tracking cameras 1902 and 1912 to compensate for the determined time offset between the video streams.

FIG. 20 illustrates an embodiment of one user 2010 wearing an XR headset 2000 who's eyes 2004 are tracking using reflections from a reflective surface 2020 that are imaged in video frames from the stereo tracking cameras 2002, in accordance with some embodiments of the present disclosure. Referring to FIG. 20, when the XR headset 2000 has outward facing stereo tracking cameras 2002 and trackable headset shape/form and is faced toward a reflective surface 2020, the stereo tracking cameras 2002 can then image the user's eyes 2004 as well as the headset's apparent shape (i.e. pose). An outside-in tracking setup such as this allows the cameras 2002 to determine how far away the user 2010 is from the reflective surface 2020 and how far the user's eyes 2004 are from the cameras 2002 and the headset 2000 itself. This set up also enables the camera tracking system 910 to estimate the eyes (e.g., pupils) poses in space relative to the headset 2000. With this information, the system will be able to render content with less warping and the user 2010 may need to spend less time adjusting the headset 2000 to avoid sharpness degradation in displayed objects and/or degradation in alignment accuracy between where displayed objects are overlaid on tracked real-world objects. These operations enable the camera tracking system 910 to compensate for when the headset 2000 shifts on the user's head, but in the case of using imaging from the reflectively surface 2020, only while the user is looking at the reflective surface 2020.

In some embodiments, the second XR headset 2000 is a reflected image from a reflective surface 2020 of the first XR headset 2000 imaged in video frames from the stereo tracking cameras 2002 located on the first XR headset 2000.

These above embodiments allow for eye tracking without the need of an additional tracking system if the headset has an inside-out tracking system and can see a reflective surface which reflects images of the headset and the user's eyes or can see another headset and the eyes of the user wearing the other headset.

FIG. 21 illustrates an embodiment of tracking coordinate systems for two XR headsets 2100 and 2110 in accordance with some embodiments of the present disclosure. All the optical recognition, tracking and pose estimation are performed by and relative to stereo cameras “CA” and “CB”. The translation and orientation relationships between the tracking cameras and headset (or headset marker) coordinate systems (T_(HA) ^(CA) and T_(HB) ^(CB)) may be calibrated in the factory or during a subsequent calibration process as may be the camera to display relationships (T_(DA) ^(CA) and T_(DB) ^(CB)). A potential advantage of applying these translation and orientation relationships between the tracking cameras and headset is that improved calibration of eye-to-display relationships can be dynamically performed and resulting improvements for where symbols are displayed on the display devices of the XR headsets may be obtained during navigated surgery.

Referring to FIG. 22, in some embodiments, the camera tracking system is further configured to operatively obtain 2204 an XR headset-to-display transform between a pose of the second XR headset and a pose of the display device of the second XR headset. The determination of the second pose of the eyes of the user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset is performed based on the second tracking information from the stereo tracking cameras located on the first XR headset and the XR headset-to-display transform.

In order for eye tracking to inform improved eye to display calibration and de-warping (T_(EA) ^(DA) and T_(EB) ^(DB)), the tracking cameras should be able to recognize and localize both a set of eyes and the corresponding headset coordinate systems in the same optical frames.

In some embodiments, the control of where information is displayed on the display device of the second XR headset based on the eye-to-display relationship, includes to adjust a projected image displayed on a see-through display screen of the display device of the second XR headset based on the eye-to-display relationship.

Significant “real-world” distortion through the displays (i.e., refraction) would add another level of complexity to properly localizing the eyes. If such distortion existed, it would advantageously be compensated for via real-world display calibration in the factory. Such calibration would be applied in the context of the tracked camera to display relationships (T_(DB) ^(CA) and T_(DA) ^(CB)).

FIG. 23 illustrates a flow chart of operations performed by a camera tracking system in accordance with some embodiments.

Referring to FIG. 23, in some embodiments the camera tracking system is further configured to operatively obtain 2300 a display-to-eye distortion transform relating optical distortion of real-world images passing through the see-through display screen of the display device of the second XR headset to where a wearer's eyes are posed relative to the see-through display screen. The camera tracking system is also further configured to operatively further control 2302 where symbols are displayed on the see-through display screen of the display device of the second XR headset based on the eye-to-display relationship and the display-to-eye distortion transform.

In some embodiments, recalibration is initiated to ensure accuracy of the displayed images by the XR headset. In one embodiment, the camera tracking system is further configured to operatively display a prompt on the display device of the second XR headset indicating that the user should look at the first XR headset responsive to expiration of a threshold recalibration time since a last calibration of the eye-to-display relationship was performed. In another embodiment, the camera tracking system is further configured to operatively display a prompt on the display device of the second XR headset indicating that the user should adjust pose of the second XR headset relative to the eyes of the user responsive to determining the second XR headset has shifted more than a threshold amount relative to the eyes of the user wearing the second XR headset.

Some other embodiments relate to the tracking of one headset to another (T_(HA) ^(HB)) via the tracking cameras. It may be the case that one headset tracking cameras are obstructed or not properly tracking in the same shared (multi-user) coordinate system. In such a situation, the ability for one headset to directly track the pose of another headset would enable improved shared AR experiences.

As explained above, In some embodiments, the second XR headset is used to perform inside-out eye tracking of the first XR headset wearer. Referring to FIG. 19, in these embodiments, the camera tracking system is further configured to operatively determine a third pose of the first XR headset 1900 relative to second stereo tracking cameras located on the second XR headset based on third tracking information from the second stereo tracking cameras. The camera tracking system is also further configured to operatively determine a fourth pose of eyes of a user wearing the first XR headset relative to the second stereo tracking cameras located on the second XR headset based on fourth tracking information from the second stereo tracking cameras. The camera tracking system is also further configured to operatively calibrate an eye-to-display relationship defining pose of the eyes of the user wearing the first XR headset to the display device of the first XR headset based on the determined third and fourth poses. The camera tracking system is also further configured to operatively control where symbols are displayed on the display device of the first XR headset based on the eye-to-display relationship.

The following embodiments relate to a computer program product including program code executable by the camera tracking system similar to embodiments discussed above.

In various embodiments, a computer program product comprising a non-transitory computer readable medium storing program code executable by a camera tracking system is operative to determine a first pose of the second XR headset relative to stereo tracking cameras located on the first XR headset based on first tracking information from the stereo tracking cameras. The program code executable by the camera tracking system is operative to also determine a second pose of eyes of a user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset based on second tracking information from the stereo tracking cameras. The program code executable by the camera tracking system is operative to also calibrate an eye-to-display relationship defining pose of the eyes of the user wearing the second XR headset to a display device of the second XR headset based on the determined first and second poses. The program code executable by the camera tracking system is operative to also control where symbols are displayed on the display device of the second XR headset based on the eye-to-display relationship.

In some embodiments, the program code executable by the camera tracking system is further operative to obtain an XR headset-to-display transform between a pose of the second XR headset and a pose of the display device of the second XR headset. The determination of the second pose of the eyes of the user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset is performed based on the second tracking information from the stereo tracking cameras located on the first XR headset and the XR headset-to-display transform.

In some embodiments, the first tracking information from the stereo tracking cameras tracks a reference array on the second XR headset. The second tracking information from the stereo tracking cameras tracks the eyes of the user wearing the second XR headset. The XR headset-to-display transform relates the pose of the reference array on the second XR headset and the pose of the display device of the second XR headset.

In some embodiments, the determination of the first pose of the second XR headset relative to the stereo tracking cameras located on the first XR headset, includes to determine first offset distances between the stereo tracking cameras located on the first XR headset and the second XR headset. The determination of the second pose of the eyes of the user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset, includes to determine second offset distances between the stereo tracking cameras located on the first XR headset and the eyes of the user. The calibration of the eye-to-display relationship defining pose of the eyes of the user wearing the second XR headset to the display device of the second XR headset, includes to determine third offset distances between the eyes of the user and the display device of the second XR headset based on the first and second offset distances.

In some embodiments, the determination of the second pose and the calibration of the eye-to-display relationship are performed responsive to detection of the eyes of the user wearing the second XR headset when imaged in video frames from the stereo tracking cameras located on the first XR headset.

In some embodiments, the control of where information is displayed on the display device of the second XR headset based on the eye-to-display relationship, includes to adjust a projected image displayed on a see-through display screen of the display device of the second XR headset based on the eye-to-display relationship.

In some embodiments, the program code executable by the camera tracking system is further operative to obtain a display-to-eye distortion transform relating optical distortion of real-world images passing through the see-through display screen of the display device of the second XR headset to where a wearer's eyes are posed relative to the see-through display screen. The program code executable by the camera tracking system is also further operative to further control where symbols are displayed on the see-through display screen of the display device of the second XR headset based on the eye-to-display relationship and the display-to-eye distortion transform.

In some embodiments, the program code executable by the camera tracking system is further operative to, responsive to expiration of a threshold recalibration time since a last calibration of the eye-to-display relationship was performed, displaying a prompt on the display device of the second XR headset indicating that the user should look at the first XR headset.

In some embodiments, the program code executable by the camera tracking system is further operative to, responsive to determining the second XR headset has shifted more than a threshold amount relative to the eyes of the user wearing the second XR headset, displaying a prompt on the display device of the second XR headset indicating that the user should adjust pose of the second XR headset relative to the eyes of the user.

In some embodiments, the program code executable by the camera tracking system is further operative to determine a third pose of the first XR headset relative to second stereo tracking cameras located on the second XR headset based on third tracking information from the second stereo tracking cameras. The program code executable by the camera tracking system is also further operative to determine a fourth pose of eyes of a user wearing the first XR headset relative to the second stereo tracking cameras located on the second XR headset based on fourth tracking information from the second stereo tracking cameras. The program code executable by the camera tracking system is also further operative to calibrate an eye-to-display relationship defining pose of the eyes of the user wearing the first XR headset to the display device of the first XR headset based on the determined third and fourth pose. The program code executable by the camera tracking system is also further operative to control where symbols are displayed on the display device of the first XR headset based on the eye-to-display relationship.

Further Definitions and Embodiments

In the above-description of various embodiments of present inventive concepts, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of present inventive concepts. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which present inventive concepts belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense expressly so defined herein.

When an element is referred to as being “connected”, “coupled”, “responsive”, or variants thereof to another element, it can be directly connected, coupled, or responsive to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected”, “directly coupled”, “directly responsive”, or variants thereof to another element, there are no intervening elements present. Like numbers refer to like elements throughout. Furthermore, “coupled”, “connected”, “responsive”, or variants thereof as used herein may include wirelessly coupled, connected, or responsive. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Well-known functions or constructions may not be described in detail for brevity and/or clarity. The term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements/operations, these elements/operations should not be limited by these terms. These terms are only used to distinguish one element/operation from another element/operation. Thus, a first element/operation in some embodiments could be termed a second element/operation in other embodiments without departing from the teachings of present inventive concepts. The same reference numerals or the same reference designators denote the same or similar elements throughout the specification.

As used herein, the terms “comprise”, “comprising”, “comprises”, “include”, “including”, “includes”, “have”, “has”, “having”, or variants thereof are open-ended, and include one or more stated features, integers, elements, steps, components or functions but does not preclude the presence or addition of one or more other features, integers, elements, steps, components, functions or groups thereof. Furthermore, as used herein, the common abbreviation “e.g.”, which derives from the Latin phrase “exempli gratia,” may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. The common abbreviation “i.e.”, which derives from the Latin phrase “id est,” may be used to specify a particular item from a more general recitation.

Example embodiments are described herein with reference to block diagrams and/or flowchart illustrations of computer-implemented methods, apparatus (systems and/or devices) and/or computer program products. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit of a general purpose computer circuit, special purpose computer circuit, and/or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions/acts specified in the block diagrams and/or flowchart block or blocks, and thereby create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block(s).

These computer program instructions may also be stored in a tangible computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of present inventive concepts may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor such as a digital signal processor, which may collectively be referred to as “circuitry,” “a module” or variants thereof.

It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of inventive concepts. Moreover, although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Many variations and modifications can be made to the embodiments without substantially departing from the principles of the present inventive concepts. All such variations and modifications are intended to be included herein within the scope of present inventive concepts. Accordingly, the above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended examples of embodiments are intended to cover all such modifications, enhancements, and other embodiments, which fall within the spirit and scope of present inventive concepts. Thus, to the maximum extent allowed by law, the scope of present inventive concepts are to be determined by the broadest permissible interpretation of the present disclosure including the following examples of embodiments and their equivalents, and shall not be restricted or limited by the foregoing detailed description. 

What is claimed is:
 1. A camera tracking system for computer assisted navigation during surgery operative to: determine a first pose of a second extended-reality (XR) headset relative to stereo tracking cameras located on a first XR headset based on first tracking information from the stereo tracking cameras; determine a second pose of eyes of a user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset based on second tracking information from the stereo tracking cameras; calibrate an eye-to-display relationship defining pose of the eyes of the user wearing the second XR headset to a display device of the second XR headset based on the determined first and second poses; and control where symbols are displayed on the display device of the second XR headset based on the eye-to-display relationship.
 2. The camera tracking system of claim 1, further operative to: obtain an XR headset-to-display transform between a pose of the second XR headset and a pose of the display device of the second XR headset, wherein the determination of the second pose of the eyes of the user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset is performed based on the second tracking information from the stereo tracking cameras located on the first XR headset and the XR headset-to-display transform.
 3. The camera tracking system of claim 2, wherein: the first tracking information from the stereo tracking cameras tracks a reference array on the second XR headset; the second tracking information from the stereo tracking cameras tracks the eyes of the user wearing the second XR headset; and the XR headset-to-display transform relates the pose of the reference array on the second XR headset and the pose of the display device of the second XR headset.
 4. The camera tracking system of claim 1, wherein: the determination of the first pose of the second XR headset relative to the stereo tracking cameras located on the first XR headset, includes to determine first offset distances between the stereo tracking cameras located on the first XR headset and the second XR headset; the determination of the second pose of the eyes of the user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset, includes to determine second offset distances between the stereo tracking cameras located on the first XR headset and the eyes of the user; and the calibration of the eye-to-display relationship defining pose of the eyes of the user wearing the second XR headset to the display device of the second XR headset, includes to determine third offset distances between the eyes of the user and the display device of the second XR headset based on the first and second offset distances.
 5. The camera tracking system of claim 1, wherein the determination of the second pose and the calibration of the eye-to-display relationship are performed responsive to detection of the eyes of the user wearing the second XR headset when imaged in video frames from the stereo tracking cameras located on the first XR headset.
 6. The camera tracking system of claim 1, wherein the second XR headset is a reflected image from a reflective surface of the first XR headset imaged in video frames from the stereo tracking cameras located on the first XR headset.
 7. The camera tracking system of claim 1, wherein: the control of where information is displayed on the display device of the second XR headset based on the eye-to-display relationship, includes to adjust a projected image displayed on a see-through display screen of the display device of the second XR headset based on the eye-to-display relationship.
 8. The camera tracking system of claim 7, further operative to: obtain a display-to-eye distortion transform relating optical distortion of real-world images passing through the see-through display screen of the display device of the second XR headset to where a wearer's eyes are posed relative to the see-through display screen, and further control where symbols are displayed on the see-through display screen of the display device of the second XR headset based on the eye-to-display relationship and the display-to-eye distortion transform.
 9. The camera tracking system of claim 1, further operative to: responsive to expiration of a threshold recalibration time since a last calibration of the eye-to-display relationship was performed, displaying a prompt on the display device of the second XR headset indicating that the user should look at the first XR headset.
 10. The camera tracking system of claim 1, further operative to: responsive to determining the second XR headset has shifted more than a threshold amount relative to the eyes of the user wearing the second XR headset, displaying a prompt on the display device of the second XR headset indicating that the user should adjust pose of the second XR headset relative to the eyes of the user.
 11. The camera tracking system of claim 1, further operative to: determine a third pose of the first XR headset relative to second stereo tracking cameras located on the second XR headset based on third tracking information from the second stereo tracking cameras; determine a fourth pose of eyes of a user wearing the first XR headset relative to the second stereo tracking cameras located on the second XR headset based on fourth tracking information from the second stereo tracking cameras; calibrate an eye-to-display relationship defining pose of the eyes of the user wearing the first XR headset to the display device of the first XR headset based on the determined third and fourth poses; and control where symbols are displayed on the display device of the first XR headset based on the eye-to-display relationship.
 12. The camera tracking system of claim 11, further operative to: perform time synchronization between video steams from the first XR headset and the second XR headset, wherein the first, second, third, and fourth poses are determined using the output of the time synchronization between the video streams.
 13. A computer program product comprising a non-transitory computer readable medium storing program code executable by a camera tracking system is operative to: determine a first pose of the second extended-reality (XR) headset relative to stereo tracking cameras located on the first XR headset based on first tracking information from the stereo tracking cameras; determine a second pose of eyes of a user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset based on second tracking information from the stereo tracking cameras; calibrate an eye-to-display relationship defining pose of the eyes of the user wearing the second XR headset to a display device of the second XR headset based on the determined first and second poses; and control where symbols are displayed on the display device of the second XR headset based on the eye-to-display relationship.
 14. The computer program product of claim 13, wherein the program code executable by the camera tracking system is further operative to: obtain an XR headset-to-display transform between a pose of the second XR headset and a pose of the display device of the second XR headset, wherein the determination of the second pose of the eyes of the user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset is performed based on the second tracking information from the stereo tracking cameras located on the first XR headset and the XR headset-to-display transform.
 15. The computer program product of claim 14, wherein: the first tracking information from the stereo tracking cameras tracks a reference array on the second XR headset; the second tracking information from the stereo tracking cameras tracks the eyes of the user wearing the second XR headset; and the XR headset-to-display transform relates the pose of the reference array on the second XR headset and the pose of the display device of the second XR headset.
 16. The computer program product of claim 13, wherein: the determination of the first pose of the second XR headset relative to the stereo tracking cameras located on the first XR headset, includes to determine first offset distances between the stereo tracking cameras located on the first XR headset and the second XR headset; the determination of the second pose of the eyes of the user wearing the second XR headset relative to the stereo tracking cameras located on the first XR headset, includes to determine second offset distances between the stereo tracking cameras located on the first XR headset and the eyes of the user; and the calibration of the eye-to-display relationship defining pose of the eyes of the user wearing the second XR headset to the display device of the second XR headset, includes to determine third offset distances between the eyes of the user and the display device of the second XR headset based on the first and second offset distances.
 17. The computer program product of claim 13, wherein the determination of the second pose and the calibration of the eye-to-display relationship are performed responsive to detection of the eyes of the user wearing the second XR headset when imaged in video frames from the stereo tracking cameras located on the first XR headset.
 18. The computer program product of claim 13, wherein the second XR headset is a reflected image from a reflective surface of the first XR headset imaged in video frames from the stereo tracking cameras located on the first XR headset.
 19. The camera tracking system of claim 13, wherein: the control of where information is displayed on the display device of the second XR headset based on the eye-to-display relationship, includes to adjust a projected image displayed on a see-through display screen of the display device of the second XR headset based on the eye-to-display relationship.
 20. The computer program product 19, wherein the program code executable by the camera tracking system is further operative to: obtain a display-to-eye distortion transform relating optical distortion of real-world images passing through the see-through display screen of the display device of the second XR headset to where a wearer's eyes are posed relative to the see-through display screen, and further control where symbols are displayed on the see-through display screen of the display device of the second XR headset based on the eye-to-display relationship and the display-to-eye distortion transform. 